I'm going through something very similar. Crushes are the best and worst feeling at the same time. I would recommend trying to meet other people and trying to better yourself and learn how to be comfortable being alone. You could be spending your time thinking about someone (that you aren't sure feels the same way) or you could use that brain power to better yourself so that you find the one. She needs to have a life outside of you, so DON'T smother her. You will murder any chances that you have with this girl by coming across as clingy and desperate.

I get you though, the thoughts are intrusive and they're intense. "Do they feel the same way" or "did I say something wrong!" The best way to find happiness in these situations is to relinquish some control and need for certainty and understand that if they don't like you, you'll live. You're whole without them and if it doesn't work out or if they don't feel the same way, no hard feelings. But build a stronger self-esteem first. You're placing way to much emphasis on what she does for you, how she makes you feel, how she will fit into your life, but have you ever considered what she wants? This sounds like a very unhealthy attachment. If you don't love yourself, you won't be able to love someone else.

My second piece of advice to you is to take a good month to sort out your shit. Make sure your house is in order and focus on you. Why do you like her? Ask yourself these questions and figure out what your intentions are. Are you ready for a relationship? Judging by your post, I'm not too sure, I'm being honest. If you really wanna go for it, tell her how you feel to get closure and if she likes you back, great! If not, oh well. I know it's tough love, but that's how you gotta be to keep yourself honest and grounded.